The formula for calculating the perimeter of a triangle is expressed as;
P = 2(l+w)
l is the length of the rectangle
w is the width of the rectangle
Given
length l = 7
width w = w
Substitute into the given values into the expression
P = 2(7+w)
Open the parenthesis
P = 2(7)+2w
P = 14 + 2w
The correct option is C